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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-06-19 21:00:51 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-06-19 21:00:51 +0000 |
commit | 6d03a247468059b0e59c821ef39e6762d4d6fc30 (patch) | |
tree | 17b9c00de2c62e68c965c742cdbc206f77a375da /arch/x86/include/asm/local.h | |
parent | Releasing progress-linux version 6.8.12-1~progress7.99u1. (diff) | |
download | linux-6d03a247468059b0e59c821ef39e6762d4d6fc30.tar.xz linux-6d03a247468059b0e59c821ef39e6762d4d6fc30.zip |
Merging upstream version 6.9.2.
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'arch/x86/include/asm/local.h')
-rw-r--r-- | arch/x86/include/asm/local.h | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/arch/x86/include/asm/local.h b/arch/x86/include/asm/local.h index 73dba8b944..59aa966dc2 100644 --- a/arch/x86/include/asm/local.h +++ b/arch/x86/include/asm/local.h @@ -131,8 +131,20 @@ static inline bool local_try_cmpxchg(local_t *l, long *old, long new) (typeof(l->a.counter) *) old, new); } -/* Always has a lock prefix */ -#define local_xchg(l, n) (xchg(&((l)->a.counter), (n))) +/* + * Implement local_xchg using CMPXCHG instruction without the LOCK prefix. + * XCHG is expensive due to the implied LOCK prefix. The processor + * cannot prefetch cachelines if XCHG is used. + */ +static __always_inline long +local_xchg(local_t *l, long n) +{ + long c = local_read(l); + + do { } while (!local_try_cmpxchg(l, &c, n)); + + return c; +} /** * local_add_unless - add unless the number is already a given value |